Functional characterization of the cardiac ryanodine receptor pore-forming region

• Published in: PloS one Vol. 8; no. 6; p. e66542
• Main Authors: Euden, Joanne, Mason, Sammy A, Williams, Alan J
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 12-06-2013; Public Library of Science (PLoS)
• Subjects: Base Sequence; Biology; Blotting, Western; Calcium; Calcium (intracellular); Calcium Channel Blockers - pharmacology; Calcium channels; Calcium release channels; Cations - metabolism; Chromatography, Gel; Conduction; Cryoelectron Microscopy; Crystallization; DNA Primers - genetics; Electron microscopy; Equivalence; Forming; Heart; Heart diseases; Ion channels; Ion Transport - drug effects; Medicine; Membranes; Models, Molecular; Molecular modelling; Molecular Sequence Data; Myocardium - metabolism; Neomycin - pharmacology; Phospholipids; Polymerase Chain Reaction; Pore formation; Potassium; Potassium channels; Protein expression; Proteins; Receptors; Rodents; Ryanodine Receptor Calcium Release Channel - chemistry; Ryanodine Receptor Calcium Release Channel - genetics; Ryanodine Receptor Calcium Release Channel - metabolism; Ryanodine receptors; Selectivity; Sequence Analysis, DNA; Sheep; Structural members; Translocation
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0066542

Ryanodine receptors are homotetrameric intracellular calcium release channels. The efficiency of these channels is underpinned by exceptional rates of cation translocation through the open channel and this is achieved at the expense of the high degree of selectivity characteristic of many other types of channel. Crystallization of prokaryotic potassium channels has provided insights into the structures and mechanisms responsible for ion selection and movement in these channels, however no equivalent structural detail is currently available for ryanodine receptors. Nevertheless both molecular modeling and cryo-electron microscopy have identified the probable pore-forming region (PFR) of the ryanodine receptor (RyR) and suggest that this region contains structural elements equivalent to those of the PFRs of potassium-selective channels. The aim of the current study was to establish if the isolated putative cardiac RyR (RyR2) PFR could form a functional ion channel. We have expressed and purified the RyR2 PFR and shown that function is retained following reconstitution into planar phospholipid bilayers. Our data provide the first direct experimental evidence to support the proposal that the conduction pathway of RyR2 is formed by structural elements equivalent to those of the potassium channel PFR.